Processes that are known or thought to be useful for the production of an optically active allyl compound include (1) once synthesizing a racemic form of a desired allyl compound, followed by optical resolution using an optically active resolving agent or an enzyme, (2) starting with an asymmetric compound, or (3) using an asymmetric catalyst.
The process (1) which uses an optically active resolving agent requires an equivalent or more amount of a resolving agent relative to an allyl compound. Moreover, complicated procedures such as crystallization, separation, and purification, are involved before obtaining an optically active allyl compound. The process (1) which uses an enzyme, while capable of yielding an allyl compound with relatively high optical purity, limits the type of a reaction substrate and the absolute configuration of a resulting allyl compound.
The process (2) is conceivable but problematic in that an optically active starting compound is not only expensive but must be used in a stoichiometric excess.
As the process (3), detailed researches have recently been done into catalytic asymmetric synthesis of an optically active allyl compound that can achieve high efficiency and asymmetric yield, as reported in Trost, B. M. & Van Vranken, D. L. Chem. Rev., 96, 395-422 (1996) and Trost, B. M. & Crawley, M. L., Chem. Rev., 103, 2921-2944 (2003). The techniques in this line are still under study.